HD4850 x2 Problems

[apologix]

hey,
i figured out that it seems to be possible to use 2 monitors while crossfirex is activated, as long as i plug in 1 monitor, enable crossfirex and then use the neighbour dvi slot.
anyway somehow under circumstances which i dont know, my secondary monitor just turns black while my primary monitor show strange vertical stripes... their colors change each time this is happening

i have the feeling its related to some overclocking, BUT when im using both monitors without crossfire or just 1 monitor with crossfirex this isnt happening even if they are also oc'ed...
both were stable at 700/1050, while crossfirex isnt combined with dual monitor usage...

does someone have a clue what could cause this problem ? oc might be a reason, but why is it stable at the other 2 setups 😱?
driverproblems or a productionfailure also seem to be options to me but i dont know

system:
qx6700
asus p5q pro
4gb ddr2
corsair 650w

 

[apologix]

hmm obviously its connected to the oc...
was working fine for some time, so i tested it again with oc... worked for 50secs -> restart -> 10secs -> restart (wasnt fast enough to set default clocks) so i disconnected one monitor and its working fine again ...
i hope this is a driver issue, since it would definately be a pain in the ass, if i cant overclock my gpus while using 2 monitors :|